Hello all!
I am very happy to be a new member and know I will enjoy the experience imensely.
I have been retired for some time but have just recently discovered the joy of astronomy and the overwhelming expanse and mystery of space.
A rank amature, I have plunked APOD on the desktop of my PC and find it not only beautiful and awesome, but a fantastic source of new knowledge and learning.
At my age a preplanned, strategic learning course might be too disciplined and boring for my temperment but, the many links in APOD provide many surprises and considerable learning.
![Rolling Eyes :roll:](./images/smilies/icon_rolleyes.gif)
Hence my first comment - What I think on this image are being called "crater chains" appear to be lines of dimples that seem very uniform and equidistant. This leads me to doubt that they were formed by the impact of objects from space but rather that they may have been formed (each instance) by such an object entering ata low angle and skipping on impact. Much as a child might skip a flat stone over the surface of a pond.
This is probably a silly idea and in no way helps explain why these "dimples" appear so uniform insize. - Perhaps we are looking at whale or other blowholes (A vent to permit the escape of air or other gas.) rather than tiger stripes.
Anyway this is a great site and the mysteries of space sure beat Agatha Christie and Ruth Rendell and their "Golden Oldies"by being forever refreshed.
Best regards,
Coolbear